One of the principal forms of firefighting equipment in use today is a vehicle customarily referred to as a pumper. Mounted upon the frame of this vehicle is a large pump which can typically receive water from either side of the vehicle, raise the pressure of the water and discharge it to either side of the vehicle. The pump may be of a single impeller design as shown in U.S. Pat. No. 3,500,961 or a multiple impeller design as shown in U.S. Pat. No. 3,726,308. Both single and multiple volute pumps have their own advantages, and the principal advantage of the single volute pump is its lower cost and simplicity of operation. However, prior art double suction, single volute pumps of the type shown in U.S. Pat. No. 3,500,961 have horizontally split housings to provide access to the impeller and shaft. This form of design therefore requires special sealing considerations where the impeller shaft passes between the castings. In addition, service of the double suction, single volute pumps presents certain problems. Thus, if the lower casting is to be removed to provide access, it is necessary to work within the space provided within a truck between the fore and aft extending main frame members. This can be avoided by removing the entire pump from the vehicl, but this in turn requires disconnection of many fluid lines. Similarly, if access is to be provided by removing the top half of the pump casing, it is also necessary to remove many fluid lines. Therefore, service on such pump designs cannot be readily performed.